1. Field of the Invention
The present invention relates to a rolled sheet of an aluminum alloy having a high strength, a high rigidity and an excellent heat resistance, and to a process for producing the same.
2. Description of the Prior Art
Conventional high-strength, heat-resistant, rolled sheets of an aluminum alloy and process for producing the same are described in the specification of Japanese Patent Laid-Open No. 62836/1988. The rolled aluminum sheet disclosed in the above specification has a composition comprising 0.10 to 5.0% by weight of Mg and 0.3 to 3.0% by weight of Mn or a composition comprising 0.10 to 5.0% by weight of Mg, 0.3 to 3.0% by weight of Mn and 0.01 to 0.30% of Zr, wherein intermetallic compounds crystallized on the surface thereof have a maximum particle size of 10 .mu.m or less. Further, the above specification discloses a process for producing the rolled sheet, wherein a melt of the above-described alloy is subjected to continuous cast rolling.
In the above-described conventional rolled sheet, there is room for improvement in the strength, rigidity and heat resistance, and the development of a rolled sheet having superior properties in respect of strength, rigidity and heat resistance has been desired in the art.